1. Field of the Invention
The present invention relates to a laser apparatus in which one or more laser beams emitted from one or more semiconductor lasers contained in a package are optically combined in an optical fiber. The present invention also relates to a method for assembling the above laser apparatus.
2. Description of the Related Art
Some known types of laser apparatuses optically combine a plurality of laser beams in a single optical fiber, and output a high-power laser beam by inputting the plurality of laser beams into the single optical fiber. For example, such laser apparatuses are disclosed in Japanese Unexamined Patent Publication Nos. 2003-347647 and 2004-045667. The disclosed laser apparatuses are basically constituted by one or more semiconductor lasers which emit a plurality of laser beams, a single optical fiber, and an optical condensing system which condenses the plurality of laser beams and makes the condensed laser beams enter the optical fiber.
In addition, in another known type of laser apparatus, a laser beam emitted from a single semiconductor laser is condensed by an optical condensing system, and is then coupled to an optical fiber. For example, such a laser apparatus is disclosed in European Patent Publication No. 0631164.
In many of the above types of laser apparatuses, the optical condensing systems and the semiconductor lasers are hermetically sealed in a package for prevention of contamination with dust and the like. In the case where such a package is used, usually, optical components constituting the optical condensing system (such as a condensing lens) are fixed to holders or other fixing members directly or indirectly fixed to the package, by using an adhesive, solder, or the like. In addition, the optical fiber is fixed to the package in such a manner that a light-entrance end of the optical fiber faces the optical condensing system. In many cases, an adhesive or solder is used for fixing the optical fiber. Further, Japanese Unexamined Patent Publication No. 2004-045667 discloses an example of a structure for fixing an optical fiber to a package with an adhesive.
However, in the case where semiconductor lasers and optical components are fixed to a package or fixing members fixed to the package as mentioned above, with an adhesive or solder, the output levels or the lifetimes of the semiconductor lasers deteriorate, and the error of the position of the condensing lens or the like increases to approximately several micrometers, although the condensing lens or the like are required to be precisely aligned with the optical fiber, and the precision of the position of the condensing lens or the like is inherently required to be as high as approximately one micrometer.